Printed circuit boards are well-known. Basically they comprise panels of insulating resin of various shapes and sizes having circuits printed thereon by known techniques. These circuits are formed of copper or other conductive metal that can be deposited through photography. They include mountings for components that are to be soldered permanently to the boards, these usually being small holes where the leads of resistors, capacitors, transistors and even transformers and electric lamps can be inserted. Soldering is effected by dipping or so-called wave soldering where the surface of the board opposite the side carrying the protruding components is passed through a flowing wave of solder. Obviously the board will normally have circuitry on both surfaces, and contacts along one or more edges to enable it to be connected into a large system.
Often these boards are intended to be inserted into narrow spaces where the bottom surface, that is, the one having the least protruding portions of the components, must clear another adjacent board.
The printed circuit boards are intended generally to be made by mass production methods and not to be serviced by varying the circuitry. In such apparatus utilizing these boards service is effected by locating the faulty board and substituting a known good one therefor.
In the manufacture of electronic apparatus utilizing extensive circuitry the technique of printed circuit board manufacture yields conveniences and economies which justify its use for situations where the circuit is to be modified after manufacture and assembly. There are situations where a given circuit board is to be used for several different purposes in the same or different systems, the functions differing from one another by the inclusion or exclusion of different parts of the circuit or even by including or excluding different components which have been built into the board during the process of automated production.
In such cases, the basic circuit may be capable of modification by simple switching provided by switch devices mounted on the circuit boards. Typically such a switch device will close a circuit by a technician screwing a metal member against the board bridging a pair of conductors on the same side of the board or establishing a connection between conductors on opposite surfaces of the board. To open the circuit one unscrews the metal member away from the board. The axial end of the member or a flange thereof performs the bridging function.
An important problem solved by the invention is the difficulty of the metal member getting free of the board, getting lost or dropping into parts of the circuit system and causing short circuits. For example, if such circuit boards with switching devices are included in a piece of equipment that is to be mounted in a vehicle, the shock and vibration could well cause a screw member having a female thread to work its way loose and fall off a stud or a member having a male thread to work its way out of a threaded socket.
Other problems exacerbating this one are those in connection with difficulty of manufacture and installation, complexity making use and manipulation inconvenient and the requirement that little space be occupied. These ancillary problems are solved by the invention in providing a highly efficient switch device that is simple to manufacture and install and which occupies very little space on the bottom of the board.